This application claims priority of DE 199 08 500.5, filed Feb. 26, 1999, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a supplementary heating system for open motor vehicles, such as roadsters or convertibles, for supplying warm air to the shoulder and neck area of vehicle occupants sitting in vehicle seats.
A known supplementary heating system of this type (German Patent Document DE 197 00 739 C1--corresponding to U.S. Pat. No. 5,839,774) has a flat design and is integrated in a wind partition which is arranged behind the backrests of the vehicle seats and covers the headrest area. The heating system heats the cold air flowing through the wind partition because of the reverse flow of the airstream and thus reduces disturbing draft air phenomena when driving without the top and thereby permits a driving without the top also at low outside temperatures. In one embodiment, the heat exchanger of the heating system in the form of an electric heating wire mesh is arranged in the frame of the wind partition. In another embodiment, the heat exchanger is attached as an inherently rigid structure in parallel to the wind partition and is fastened to the latter by means of fastening elements.
In the case of an also known supplementary heating system of this type (German Patent Document DE 92 01 474 U1), for reducing the draft air phenomena which are bothersome to the vehicle occupants when driving with an open top, air currents are supplied in a targeted manner to the vehicle occupants shoulder and neck area, which air currents flow out of an air outflow device which is arranged in the headrest area of the vehicle seats and is directed diagonally upwards toward the rear. For generating these air currents, air is collected from inflow openings provided on the vehicle and is supplied, as the result of ram pressure, to the air outflow device.
Both supplementary heaters have the disadvantage that, when the vehicle is driving slowly or is stopped, for example, in front of a traffic light, the warm air supply to the vehicle occupants' shoulder and neck area will no longer be sufficient.
It is an object of the invention to improve a supplementary heater of the initially mentioned type such that, independently of the momentary operating mode of the vehicle, a sufficient warm air supply to the vehicle occupants' shoulder and neck area will always be ensured and thus, when driving with an open top, draft phenomena from the rear are compensated at any time.
According to the invention, the object is achieved by providing a supplementary heating system of the above-mentioned type, wherein a heating module is assigned to each vehicle seat, and each heating module comprises: a heat exchanger, an air outflow nozzle arranged downstream of the heat exchanger and having an air outflow direction into an occupant shoulder and neck area, an airstream inflow opening arranged upstream of the heat exchanger and having an inflow funnel exposed to aerodynamic return or reverse flow of an outside airstream, and a fan air inflow opening arranged upstream of the heat exchanger and separated from the airstream inflow opening.
The supplementary heating system for open vehicles according to the invention has the advantage that the fan air boosts the dynamic heating by way of the airstream and, also when there is no airstream, ensures a supply of warm air to the vehicle occupants' neck and shoulder area. The dynamic air and the fan air act upon the same heat exchanger, are heated there and, by way of the same outflow nozzle, arrive in the respective vehicle occupant's shoulder and neck area.
Advantageous embodiments of the supplementary heating system according to the invention with expedient developments and further developments of the invention are described herein and in the claims.
According to a preferred embodiment of the invention, the heat exchanger is accommodated in a modular housing on which the air outflow nozzle and the inflow funnel are constructed. The separation of the airstream inflow opening and the fan air inflow opening takes place by means of a separating wall which connects a smaller portion of the air inlet surface of the heat exchanger with the fan air inflow opening, and the larger portion of the air inlet surface of the heat exchanger with the airstream inflow opening. This separating wall prevents that the fan air already flows out into the open in front of the heat exchanger. Since, during a slow drive or when the vehicle is stopped, only a small amount of warm air is required for a sufficient warming of the shoulder and neck area, the small heat exchanger surface acted upon by the fan air will be completely sufficient. This also has the advantage that only a low fan output is required and the fan may therefore have a small size.
According to advantageous embodiments of the invention, the separating wall is conceived as a swivellable air flap which, in its one swivelling end position, is capable of completely covering the airstream inflow opening. The air flap controls the dynamic air quantity and is simultaneously a guiding surface for the fan to the heat exchanger.
According to an advantageous embodiments of the invention, two air blow-out connection pieces of a single fan, which is conceived as a radial-flow fan, which are offset with respect to one another in the circumferential direction by approximately 180.degree., are connected to both fan air inlet openings. Such a fan construction is particularly suitable for vehicles with narrow installation conditions and supplies a sufficient amount of air while the electric efficiency is good.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.